1. Field of the Invention
The present invention relates to a method and apparatus for preventing a malfunction of a disc drive, and more particularly, to a method and apparatus for preventing a malfunction of a disc drive due to performing a correction function for a minimum pit length when the disc drive is in an unstable operative state.
2. Description of the Related Art
As the operation speeds of optical disc drives continue to increase, radio frequency (RF) signals more frequently deteriorate due to the limitation of the speed of optical pickups for reading a disc. In particular, a minimum pit length signal having the highest frequency is easily deteriorated. If reproduction signals of the RF signals such as the minimum pit length signal are deteriorated, the reproduction quality of a disc drive is reduced. The minimum pit length can be set to 3T. Here, T represents a period of one bit clock.
A conventional disc drive has a correction function for a minimum pit length employing a level or a phase of an RF signal reproduced from the disc drive. Thus, if the reproduced RF signal is abnormal due to the unstable operation of the disc drive, an abnormal correction result for the minimum pit length is obtained. For example, if the operative state of the disc drive is unstable due to an external impact, an electric shock, a stop operation of the disc drive, and an error of a focus lock operation, etc., the reproduced RF signal may be abnormal. If the reproduced RF signal is abnormal, an error may be generated in a correction result for the minimum pit length with respect to the reproduced RF signal, or a malfunction of the disc drive may occur due to the abnormally performed correction function.
For example, if the reproduced RF signal is not synchronized due to a physical impact, the correction function for the minimum pit length is not performed correctly and the disc drive malfunctions. Further, if the RF signal is generated by mistakenly recognizing a speck on the disc as a minimum pit length signal, an error is generated in a correction result for the erroneous minimum pit length so that an error correction operation performed in a digital signal processing unit included in the disc drive is abnormally performed and the disc drive malfunctions.
If a disc is loaded into a disc drive having the capability to perform the correction function, however, the correction function is turned on irrespective of the operative state of the disc drive. Thus, a malfunction of the disc drive may occur due to the above-described problems.